As a fuser used in image forming apparatuses such as a copying machine and a printer, there is a fuser configured to insert a sheet through a nip formed between a pair of rollers including a heating roller and a pressing roller or between a heating belt and the pressing roller and heat, press, and fix a toner image on the sheet. As the fuser configured to perform heating, pressing, and fixing, in recent years, there is a device configured to feed induction current to a metal conductive layer on the surface of the heating roller or the heating belt to generate heat in order to realize saving of energy.
However, in the fuser configured to generate heat in the metal conductive layer with the induction current, when a heat capacity of the metal conductive layer is small, there is a marked temperature difference in surface temperature of the heating roller or the heating belt between an area where a sheet comes into contact with the heating roller or the heating belt and an area where the sheet does not come into contact with the heating roller or the heating belt. When there is marked temperature difference in the surface temperature of the heating roller or the heating belt, it is likely that stable fixing performance is not obtained and gloss unevenness occurs in a fixed image.
Therefore, there is a demand for development of a fuser that can stably maintain fixing performance, realize saving of energy, improve productivity of an image forming apparatus, and obtain a high-quality fixed image without gloss unevenness even when a heating roller or a heating belt has a small heat capacity.